Match List I with List II
| LIST I (EM waves) | LIST II (Source of production) | ||
|---|---|---|---|
| A. | Visible light | I. | Excitation of inner shell electrons |
| B. | X-rays | II. | Nuclear origin |
| C. | UV rays | III. | Excitation of valence electrons in atoms |
| D. | γ-rays | IV. | To bombard a metal target by high energy electrons |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A-III, B-IV, C-I, D-II
Each region of the electromagnetic spectrum has its own characteristic source, from atomic electrons for the longer waves to the nucleus for the shortest.
(A) Visible light — this matches (III) Excitation of valence electrons in atoms. Outer (valence) electrons that drop to a lower level emit photons in the visible range.
(B) X-rays — this matches (IV) To bombard a metal target by high energy electrons. X-rays are produced when fast electrons are stopped suddenly by a metal target in an X-ray tube.
(C) UV rays — this matches (I) Excitation of inner shell electrons. In the textbook table, ultraviolet is produced by inner shell electrons moving from one energy level to a lower level.
(D) γ-rays — this matches (II) Nuclear origin. They are emitted in radioactive decay and other nuclear transitions.
NCERT (2026-27):
X-Rays – “… One common way to generate X-rays is to bombard a metal target by high energy electrons.”
Gamma Rays – “… This high frequency radiation is produced in nuclear reactions and also emitted by radioactive nuclei. … Table 8.1 summarises different types of electromagnetic waves, their production and detections.”
| Type | Wavelength range | Production | Detection |
|---|---|---|---|
| Radio | > 0.1 m | Rapid acceleration and decelerations of electrons in aerials | Receiver’s aerials |
| Microwave | 0.1m to 1 mm | Klystron valve or magnetron valve | Point contact diodes |
| Infra-red | 1mm to 700 nm | Vibration of atoms and molecules | Thermopiles Bolometer, Infrared photographic film |
| Light | 700 nm to 400 nm | Electrons in atoms emit light when they move from one energy level to a lower energy level | The eye Photocells Photographic film |
| Ultraviolet | 400 nm to 1nm | Inner shell electrons in atoms moving from one energy level to a lower level | Photocells Photographic film |
| X-rays | 1nm to 10-3 nm | X-ray tubes or inner shell electrons | Photographic film Geiger tubes Ionisation chamber |
| Gamma rays | <10-3 nm | Radioactive decay of the nucleus | -do- |